1. Field of the Invention
The present invention relates to portable lighting devices such as floodlights, flashlights, key-chain lights and laser pointers and in particular relates to portable lighting devices having touch sensitive activation. While the present invention relates to all portable lighting devices, reference will be made throughout this specification to the preferred embodiment of a flashlight by way of example only.
2. Prior Art
It is known in the art to use manual switches such as pushbuttons, sliding switches, and the like to turn flashlights on and off. Since their inception, flashlights have incorporated manual switches that require manipulation by the user's fingers. In recent years, flashlights and other lights have been developed in the art to create touch sensitive “switches” from exposed terminals of an open circuit intended to be electrically bridged through the conductive medium of some portion of a user's body. For example, U.S. Pat. No. 6,388,390 (Rachwal) provides a flashlight that has two touch sensitive switches, either of which can be bridged by a user's finger. The patent describes how the user presses a finger against the exposed terminals to control the intensity of light emitted. Rachwal describes a touch sensitive switch apparatus that includes first and second terminals, which are engaged by the user to increase the intensity of the light. In addition, third and fourth terminals are engaged by the user to decrease the intensity of the light.
Other prior art discloses touch sensitive trigger circuits where conductive terminals are used as part of a switch or “trigger point”. U.S. Pat. No. 5,973,420 (Kaiserman) and U.S. Pat. No. 5,455,749 (Ferber) describe a wide range of electrical devices that utilize conductive compositions that may be painted, printed, screened, coated, or otherwise applied to non-conductive articles, creating circuitry on the surface of those articles. Both patents describe leaving open circuit “trigger points” in the circuitry that can be electrically bridged by a user's finger or other conductive objects. This electrical bridging activates LEDs, sound modules, or other responsive circuit elements.
U.S. Pat. No. 5,685,632 (Schaller) describes using conductive plastic to form selected portions of a flashlight such as battery housings or tailcaps in order to simplify construction. While Schaller is not directed to touch sensitive activation, the flashlight and conductive plastics described are relevant prior art.
The abovementioned prior art flashlights are awkward to use. Inevitably, the user must pick the flashlight up, then rotate the flashlight around, find and actuate the activation switch. While prior art flashlights with touch sensitive switches have advantages over mechanical switches, the user must still rotate the flashlight, find the touch sensitive switch, and then push it. In some instances, touch sensitive switches exacerbate the problem because they may be harder to locate than protruding mechanical switches. Indeed, devices taught by Kaiserman specifically use clear conductive composites to create “magical or mysterious” trigger points. Likewise, U.S. Pat. No. 6,054,156 (Rudell) describes novelty items that mysteriously activate a light or sound when a user uses the novelty item. The novelty items have small nodes bridged via some intermediary substance such as a drink or frozen drink. Once bridged, the completed circuit includes: the first node, the drink, the user's mouth body and hand, and then to a second node. The novelty item ‘mysteriously’ generates a light or sound when the user licks the frozen drink, providing that one of their hands is also properly abutted against the electrical node.
The open circuit nodes of touch sensitive switches described above are taught to be small, because they are particularly susceptible to inadvertent activation by accidentally making contact with other objects. Additionally, touch sensitive circuit nodes are typically close to each other and on a substantially flat surface, such that a single finger may bridge the gap, which inevitably raises the likelihood of inadvertent activation.
Locating the activation switch in prior art flashlights is particularly problematic in that the reason the user usually needs the flashlight is that only limited ambient light exists. In use, it is often too dark to visually locate the flashlight, let alone find the activation switch. Even when a user can find the activation switch, there is a certain level of dexterity that is assumed in being able to manually manipulate the switch. Elderly users or users suffering from arthritis, for example, can be considerably challenged by finding and merely placing a finger onto a touch sensitive switch.
The most able users have also traditionally been frustrated by having to activate prior art flashlights. For example, consider a mechanic who has only one hand available to manipulate a flashlight but picks it up with the activation switch on the wrong side. Worse yet are prior art flashlights requiring two hands to activate, for example by twisting one portion of the flashlight relative to another, such as commonly used by police and military forces, for example as described in U.S. Pat. No. 6,802,624 (Maglica). The problems of activating flashlights of the prior art can become serious during emergency situations where valuable time can be wasted in nervously trying to find and manipulate a flashlight's activation switch.
The present invention seeks to provide a portable lighting device that will ameliorate or overcome at least one of the deficiencies of the prior art.